You can't find the initial velocity knowing only the displacement and final velocity. You need additional information, such as:

* Time: Knowing the time it takes for the object to travel the displacement allows you to use kinematic equations to solve for initial velocity.

* Acceleration: If you know the constant acceleration acting on the object, you can use kinematic equations to find the initial velocity.

Here's why:

* Displacement: Tells you the net change in position, not the speed or direction of the object at any specific point.

* Final velocity: Tells you the velocity at the end of the motion, but doesn't reveal how the velocity changed throughout the motion.

Here's how you can find initial velocity with additional information:

1. Using Time and Displacement:

* Equation: v² = u² + 2as (where 'v' is final velocity, 'u' is initial velocity, 'a' is acceleration, and 's' is displacement)

* Rearranging for initial velocity (u): u = √(v² - 2as)

2. Using Acceleration and Displacement:

* Equation: s = ut + (1/2)at² (where 't' is time)

* Rearranging for initial velocity (u): u = (s - (1/2)at²) / t

Remember:

* These equations are for motion with constant acceleration.

* Make sure you use the correct sign conventions for displacement, velocity, and acceleration (positive or negative).

Let me know if you have any other physics questions!